Air cooled piston



Marh 14, 1939.

AIR COOLED PISTON`r Filed Nov. 19,1957

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m5. A'iToRNEY March 14, 1939. c. J. HAMMERsMlTH AIR cooLED PIsToN Filed'Nov. 19, 1937 2 sheets-sheet 2 lNvENToR Hommersmljfh uba/Q.

ORNEY Charles J.

Patented Meer. lei,

unir ares 3,150,741@ @@EAEJD? FHS'IMDN Charles .EL Haersmith, llliollis, N. Y. Application November lil, 1,1937, Serial No. 1175,378

5 Cla My present invention relates to an improvement in pistons, and more particularly, to an improved air cooled piston for internal combustion engines, air compressors, andsimilar devices.

'Ihe important construction of a device of this type, wherein pressure or vacuum devices for creating a now of cooling medium through the pistion are dispensed with and the device is built as an integral part of the engine or compressor, and in which the movement of the piston in the operation of the device creates the circulation of cooling medium for cooling the piston, and thereby preventing excessive heating of the lubricant used in connection with the machine.

Another feature of my invention is an improved form of piston which has access to the source of supply of cooling medium, such as the atmosphere at all times during the stroke of the piston, during its working cycle.

A still further feature of`my invention is an improved form of piston, wherein the cooling medium, such as atmospheric air, is circulated completely around the piston, and after so circulating, is utilized to cool or maintain at proper temperature the top or crown of the piston.

A still further feature is an improved form of piston, wherein a cooling medium is circulated throughout the interior of the piston, and particularly around the bearings for the wrist pin, to

thereby maintain the wrist pin in relatively cool condition and to thus prevent excessive Wear of the wrist pin itself and the bearings therefor in the piston.

Other features of the invention, and novel features of the construction; and arrangement of parts by means of which the present invention is carried out, will appear more particularly as the description of the invention progresses.

vIn the accompanying drawings, Fig. 1 is a vertical sectional elevation through one of the cylinders of anI internal combustion engine, showing my improved piston in elevation and. illustrating lthe circulation of cooling medium therethrough;

Fig. 2 is a sectional plan view on theline 2--2 of Fig. 1;

Fig. 3 is a sectional elevation on an enlarged scale, as compared with Figs. l and 2 of my improved air cooled piston and the cylinder'with which the same is associated, the section being taken in a plane through the wrist pin bearings;

Fig. 4 is a sectional elevation of the piston taken on the line --i o Fig. 3;

Fig. 5 is a bottom plan view of the piston illustrated in Figs. l, 3 and et;

(Cl. 12S-176) Fig. 6 is a sectional plan view on the line 6 6 of Fig. 4;

Fig. 7 is a sectional plan view similar to Fig. 6, but of a modiied form of the piston;

Fig. 8 is a sectional elevation through av modi- 5 fied form of piston;

Fig. 9 is a sectional plan view on the line 9-9 of Fig. 8;

Fig. 10 is a sectional elevation of a still further modied form of my invention; and l0 Fig. l1 is a sectional elevation of a still further modied form of my invention.

`Referring to the drawings and particularly to Figs. l, 2, 3 and 4, lil designates in its entirety, an internal combustion engine comprising a 15 crankrcase ii, on which is mounted the cylinder block l2; such cylinder block having, as shown in Fig. 2, a plurality of cylinders cast en block. The upper parts of the cylinders l2 are surrounded by the usual water jacket i3 and the open end of the 20 cylinders is closed by the water cooled cylinder head it, such cylinder head carrying the various spark plugs l5 and by means of which the charge of propelling gas is exploded. The cylinder head I4 has therein, in conjunction with the upper end 25 of the cylinder i3, the combustion chamber it through which the propelling gas is admitted and exhausted by means of the various valves i l, such combustion chamber i6 being connected through the intake valve with a carburetor or similar device i8, and this carburetor or similar device I8 is connected by means of the exible conduit I3 with the crank case li.

In the crank case i i is mounted the usual main drive shaft 2U, to which are connected the con- 35 necting rods 2 i, one of'such rods being utilized, as is usual, for each of the pistons 22.

The pistons which form the subject matter of my present invention are illustrated in detail in Figs. 3 and 4 and referring specically to such 40 gures, it will be noted that the pistons comprise a head 23, which is a sliding lt in the cylindersl l2, the usual piston rings Qtbeing employed to make a uid tight joint between the head 23 and the cylinder walls.

Formed integral with the head 23, is a central section 25 which extends downwardly as shown, merging into webs 26, and intermediate the ends of such webs, is formed the wrist pin bearings 2l, such bearings being in alignment with each other 50 as clearly shown in Fig. 3. Formed integral with the webs 25 is a substantiallycylindrical inner skirt 23 and a cylindrical outer skirt '29, the outer skirt 23 being a. sliding fit in the cylinder t2.

.et radially opposite ends or sides of skirt 29, is formed a slot of appropriate width and length, so that regardless of the position of the piston in the cylinder l2, such slots will always be in communication with ports 3l in the wall of the pistons l2.

For convenience in manufacture and assembly, the inner skirt 28 is perforated in alignment with the wrist pin bearings 21, as indicated by the reference numeral 32, and such perforations are afterwards closed by means of a plate 33 held in position by a spring 38, as shown in Fig. 3. This construction prevents seepage of cooling medium through the inner skirt 28 into the interior of the piston. The inner skirt 28 and outer skirt 3| are concentric and thereby form an annular chamber extending circumferentially around the piston, and, as shown in Fig. 3, such chamber is open at its lower end but may be closed by an annular ring 3i or, should it be preferred, the lower end may be closed by integrally casting the inner and outer skirts together.

The annular chamber above referred to, is connected to the upper or head portion 23 of the piston by means of integrally cast passages 35 which join together at their upper ends, as indi-l cated at 36, and'connect directly with a centrally arranged chamber 31 beneath the upper surface of the head 23. The chamber 31 is connected by a plurality of orices 38, with the interior of the piston or specifically with the interior of the inner skirt 28, and pass downwardly in the direction indicated by the arrows as shown in Figs. 3 and 4 and, on reference to such gures, it will be noted that the arrows show that the cooling uid has air contact with the under surface of the upper portion of the head 23 and thence passes downwardly into the interior of the piston around the bearings 21.

From the piston, the `cooling air, having performed its function, passes downwardly into the crank case il, from which it is drawn through the fiexible conduit i9 into the carburetor i8. To prevent excess of oil being drawn through the iexible conduit i9, I preferably provide balile plates 39 at the entrance end of the iiexible conduit i9, such excess -of oil being drawn out from the air and passing backward into the crank case il.

The air which is drawn through the ports 3i is preferably drawn through an air scrubber and thence through a manifold lill, from which it is branched cif by the tubes 42 into the various cylinders i2.

Referring to Fig. 1, there is shown a slight modification of the structure above illustratedl and described and wherein both the inner skirt 28 and the outer skirt 29 are of the expanding type, such expansion being obtained by having one portion i3 of the inner skirt 28 overlapping another portion i9 thereof, while the outer skirt 29 is made flexible by the overlapping portion d5 thereof cooperating with the portion 46. v

In Fig. 7, the slots 30 are clearly shown in the outer skirt 29 in alignment with the wrist pin bearings 21 and such figure also shows the perforations or orifices in the inner skirt and before the wrist pin is assembled in position therein.

In Figs. 8, 9 and 10 is shown a further modification of my invention and in which figures, the head 23 of the piston is connected by means of the central portion 6' to the' outer skirt 29. Formed integral with the outer skirt' 29 and on the interior thereof and diametrically arranged with respect to the piston, are the chambers 46 and d1, the chamber d5 connecting with the chamber d8 in the head 23 by means of a conduit or passage 49 and said central chamber 468 connecting with the chamberv 61 through a conduit or passage 50.

In this modification of the invention, there is no annular chamber but cooling air passing in through the slot 5,0 into the chamber 46, which passes upwardly through the passage 89 into the chamber 4B, thence across the width of the piston downwardly through the passage 5D into the chamber i1 and outwardly through the other slot 30. This form of my invention is adapted to be used in a situation where it is not desired to have the cooling fluid pass into the crank case of the machine with which it is to be associated.

In Fig. l1 is shown a still further modification of my invention, in which the head 23 of the piston has the chamber 5i formed beneath the under surface thereof, and which chamber is connected by a central passage 52 to the interior of the piston.

The annular chamber formed by the outer skirt 29 and inner skirt 28 is connected to the central chamber 5l by the passages 53, and such passages are so arranged that cooling fluid passing from lthe chamber between the inner and outer skirts 29 and 28 respectively now upwardly along the outside wall of the head, thence across to the center thereof and downwardly through the passage 52 into the interior of the piston.

Whereas I have described my invention by reference to specific forms thereof it will be understood that many changes and modifications may be made without departing from the spirit of the invention.

I claim:

l. An improved air cooled piston comprising an inner skirt and an outer skirt concentrically arranged with respect to each-other and forming Y an annular chamber therebetween, a head integrally formed at the top of said inner and outer skirt, a chamber formed in the head, passages connecting the annular chamber with the chamber in the head, means for permitting ingress of cooling fluid to the annular chamber and means connecting the chamber in the head with the interior of the piston.

2. In combination with the cylinder of an engine or compressor having a port open to the atmosphere communicating with the interior thereof, a piston comprising an inner and an Outer skirt spaced apart from each other and forming an annular chamber therebetween, an elongated slot in the outer skirt of the piston and communicating at all times with the port in the cylinder wall, a chamber formed in the head of the piston and communicating with the annular chamber and with the interior of the piston within the inner skirt whereby cooling fluid upon movement of the piston within the cylinder is drawn throughthe port into the annular chamberv and thence into the central chamber and downwardly through the interior of the piston.

3. In combination with the cylinder of an engine or compressor having a port extending through the cylinder wall, a piston having an inner skirt and an outer skirt concentrcally arranged and spaced apart from each other to thereby form an annular chamber therebetween, a central chamber in the head of said piston, ports formed in the wall of said chamber communicating with the interior of the piston and passages formed integral with the piston structure and connecting the annular chamber with the chamber in the head of the piston.

4. The combination in an internal combustion engine having a cylinder, a port o'pen to the atmosphere formed in the wall of said cylinder, a piston mounted for reciprocation in said cylinder and comprising inner and outer" skirts spaced from eachother and dening an annular chamber, a slot formed in the outer skirt Vand of a length to register with the port in the cylinder wall in all positions of-the piston therein, means for supplying air from the atmosphere to the port and thence to the annular chamber, and conduits formed in the pistonl for leading the air from the annular chamber upon reciprocation of the piston into the crank case of the engine.

5. The combination in an internal combustion engine having a cylinder and a crank case', ports open freely to the atmosphere formed in the' wall of said cylinder at diametrically opposite sides thereof, of a piston mounted for reciprocation in said cylinder and comprising inner and youter skirts lspaced from each other and defining an annular chamber, slots formed in the outer skirt at diametrical-ly opposite sides thereof and in alignment with the ports in the cylinder wall, and of a length to register with the ports in the cylinder wall in all positions of the piston therein, means for supplying air from the atmosphere to the ports and thence toA the annular chamber, and conduits formed in the piston for leading the air from the annular chamber into the crank case of the engine upon reciprocation of the piston.

CHARLES J. HAMMERSMITH. I 

